Fuse



March 16, 1941. T. BlRKENMAn-:R

Filed May 5l, 1939 2 Sheets-Sheet l Mmh1s,1941. y

. T. BIRKENMAIER FUSE Filed May 31, 1939 2 Sheets-Sheet 2 Patented Mar. 18, 1941 UNITED STATES PATENT OFFICE FUSE corporation of Missouri Application May 31, 1939, Serial No. 276,523

6 Claims.

This invention relates to fuses, and with re gard to certain more specific features, to automatically releasing fuse switches.

Among the several objects of the invention maybe noted the provision ,of an improvement upon the apparatus shown in United States Patent 2,000,876, dated May 7, 1935, issued to Lester P. Boll etal.; the provisions of simple and more economical apparatus of the class described which is also more positive and reliable in operation; and the provision of apparatus of this class which may be re-fused and operated with more facility. Other objects will -be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application o'f which will be indicated in the following claims.

1n the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a side elevation of the device shown in operating condition, the dotted lines indicating lan initial released condition;

Fig. 2 is a View similar to Fig; 1 showing a final released condition;

Fig. 3 is a fragmentary side .elevation showing theprocess of applying a fuse holder assembly -to certain fixed supports;

Fig. 4 is a longitudinal section of a fuse holder taken substantially on line 4-4 of Fig. 1; and,

Fig. 5 is a fragmentary view of the lower portions of Fig. 1 but viewed from the opposite side.

Similar reference characters indicate corresponding parts throughout the several views of th'e drawings.

Referring now more particularly to Fig. 1, there is shown at numeral I an insulator held by a support 3. At its upper end the insulator I is provided with a conducting clamp 5 for holding a pair of spring conducting arms or cantilever extensions 1. The clamp 5 has attached thereto by means of a connector 3 a line wire II. The arms 1 are spaced and separated toward their free ends (see Fig. 4). They are heldin spaced relationship by a. spacing clamp 2. The arms or extensions 1 in effect comprise a springing line terminal. When downwardly tensioned they assume the solid-line position of Fig. 1; otherwise the dotted-line position. They are provided with downwardly-directed cam ends 39 and notches or crimps |03.

At the lower end of the insulator I is attached (Cl. 20G-114) a conducting member I3 which constitutes a lower rigid line terminal. Another line wire I5 attached by means of a connector I1. This lower, rigid terminal I3 is provided with spaced, forwardly-directed wall portions I9, each formed 5 with a ledge`2I adjacent a wide mouth 23 of a slot indicated in general at 25. Each slot 25 has a downwardly-extending narrow portion 21 and a lower forwardly-directed circular notch, 29. At 3| is indicated in general a fuse holder. This consists of an insulating expulsion tube 33 Within which is preferably a horn fibre liner 35. Attached near, but spaced from, the lower end 31 of the tube 33 is a fixed conducting collar 39. Its holding pin is shown at 4I. This collar is conducting and constitutes a lower, non-resilient, terminal-engaging element. It carries oppositely located conducting gudgeons 43 and 45, the former being larger than the latter. These gudgeons are located on the same center line, and are each generally circular in form, but include a partial flat 41 or 49, as the case may be. One side of the sleeve 39 is provided with an eye 5I and an extension 53.A The eye 5I is completed by a support 55 upon which is located a manually-operable fuse terminal 51. The extension 53 has pivoted thereto a platen 59 which may swing adjacent the tube end 31. The platen 59 is normally biased away from the lower end of the tube by means of a coil spring 58. A stop 60, cooperating with a notch 62, limits the motion of the platen to the dotted-line position shown in Fig. 5.

Fastened to the upper end of the tube 33, as shown at 6I, is a xed sleeve 63 in which are '35 laterally-located guide slots (Fig. 4).

Slidably mounted for limited movement upon the sleeve 63 is a conducting cap 61, to which are attached shoes 69 which slide respectively in the slots 65. The outside screw fasteners 1I for the shoes 69 are removable, as are also the shoes (through openings 10), so that the cap 61 may be applied to and removed from the sleeve 63. Before application of the cap on the sleeve, a compression spring 13 is inserted to react/between the top of the sleeve 63 and the top 15 of the cap 61. The cap is flared at the bottom as shown at 11 to provide weather protection.

The upper end of the cap 61 is provided with a threaded inlet 19so that a fuse link 8l may be threaded therethrough. Its conducting head 83 is adapted to rest upon the edge of the inlet. The threaded cap 85 serves to hold in place the head 83. The cap 61 is also provided with-55 nected by a fusible section 9|.

gudgeons 93 which are in the plane of the gudgeons 43 and 45.

'I'he fuse link 8| is provided with an upper leader 81 and a lower flexible leader 89 con- The fusible section 9| is preferably near the upper end of the holder, as shown, though not necessarily so. The lower leader 89 extends from the open end 31 of the tube 33 and around the platen 59 and is connected to the terminal 51. During-application of thefuse link, it is pulled down through the tube so as to compress the spring 13 as far as possible and to bias the platen 59 into the position shown in Fig. 1. This draws down the gudgeons 93 of the cap Blite a position as close as they can approach the gudgeons 03 and 45.

Operation is as follows:

The fuse link 8| is rs't threaded into the fuse holder through the inlet 19 as above described. The cap 81 is pulled down by means of the fuse link and the latter is fastened at 51 after being threaded over platen 59 to hold up the latter. and supported upon the lug 95 of a linemans stick 91 (see Fig. 3). The lower gudgeons 43 and 45 are then Aapplied to the mouths 23 of the slots 25 with their ats 41, 49 foremost. It will be understood that the respective mouths of the v respective slots are wide enough just to slidably accommodate the differently sized gudgeons. 'I'his is true of other parts of slots to be described.. By means of the differently sized gudgeons, reversal of the fuse holder is prevented during application.

After entering the mouths 23 the gudgeons 93 and 45 slide down the narrower portions 21 to the notches 29.

The fuse holder is then rotated upwardly counterclockwise to the position shown in Fig. 1. For this purpose the lug 95 may be applied to the eye I0! which is rigidly formed on the sleeve 63. This causes the gudgeons 93 to strike upon about the central portion of the downwardly-directed ends 99 of the spring terminals 1 (see the dotted lines and the arrow in Fig. 1).

As the extension 99 is traversed, the gudgeons 93 force down the arms of the Spring terminals 1 and nally seat in notches |03. The induced tension in the terminals 1 tends to pull up the fuse holder, including the gudgeons 43 and 45. Since, however, the gudgeons 43 and 45 have rotated to the position such'that the ats 41 are in the notches 29, and since the vertical portions 21 of the grooves are too narrow to accommodate the non-nat widths of the lower gudgeons, the latter are locked against withdrawal by means of the pull from the spring terminals 1.

Upon overload, the fuse melts at the fusible section 9|. At the time of melting it is under the tension of thespring 13 and of the spring terminals 1. Upon melting, expansion of spring 13 and the rising of spring terminals 1 fromv the solid-line position to the dotted-line position (Fig. 1) results in the gudgeons 93 being raised. This raises the cap 61 and causes instantaneous separation of the fuse link at the fusible portion. Promptly the platen 59 also springs down to` withdraw the lower leader 89 While the generated gases (if any) tend to accelerate the lower leaderoutwardly. Expulsive gases generally form upon the heavier overloads, but it is to be understood that the device is effective in the absence of expulsive action, such as in the case of so-called dragging over'loads.

The fuse holder is then inverted After the raising action of the spring terminals 1 has been exhausted, the spring 13 follows up the action so as to hold the gudgeons 93 clear of the notches |03, as shown by the dotted lines in connection with the fuse holder in Fig. 1. Thereafter, the fuse holder, under the vaction of gravity, rotates clockwise to the position shown in Fig. 2. This has the eiect of placing the ats d1 and t9 so that the gudgeons 43 and 95 may be moved atwise up through the narrower slots 21 and laterally out of the slots Z5 and finally out of the mouths 23. 'Ihe holder may then be re-fused for re-application.

It will be seen that the relatively light spring 13 insures that the gudgeons 93 will hold clear of the notches |03. However, under some design conditions, where the inertia of the cap 61,is

proper, it is possible for the motion of the cap when once instigated by the action of the spring terminals 1 to move clear and to fall outwardly before dropping back into position in the notches |03. However, the presence of the spring 13 inmovable line terminal comprising a springing cantilever biased in a direction away from the fixed line terminal, a fuse holder, a xed terminal-engaging element on one end of the fuse holder having a rotary support on the xed line terminal, a movable terminal-engaging element at the other end of the fuse holder, a fuse link in the holder connecting the xed and movable terminal-engaging elements and holding them relatively closely together, the parts being arranged so that upon rotation of the fuse holder with respect to the fixed line terminal, said movable terminal-.engaging element will deflect the cantilever toward the fixed line terminal to tension the fuse link in the fuse holder.

2. A fuse comprising a xed line terminal and a movable line terminal spaced therefrom, said movable line terminal comprising a springing `cantilever biased in a direction away from the fixed line terminal, a fuse holder, a fixed terminal-engaging element on one end of the fuse holder having a rotary support on the fixed line terminal, a` movable terminal-engaging element at the other end of the fuse holder, a fuse link in the holder connecting the fixed and movable terminal-engaging elements and holding them relatively closely together, the parts being arranged so that upon rotation of the fuse holder with respect to the fixed line terminal, said movable terminal-engaging element will deflect the cantilever toward the xed line terminal to tension the fuse link, the contact between the movable terminal-engaging element and said cantilever line terminal being substantially non-frictional, and the movement of the movable terminal-engaging element being such as to clear the biased position of the cantilever when the fuse link is broken, whereby the fuse holder may thereafter rotate to an open position.

3. A fuse comprising a lower xed line terminal, an upper springing cantilever line terminal "``connecting said terminal-engaging elements and holding them relatively closely together, the up- Per cantilever line terminal and the movable terminal-engaging element being related so that l5 when the fuse holder is rotated into closed-circuit position the cantilever is deflected to bias the movable terminal-engaging element upwardly and to tension the fuse link, the movement of the movable terminal-engaging element being 20 such as to clear the cantilever in its normal operatng position when the fuse link separates.

4. A fuse comprising a lower fixed line terminal, an upper springing cantilever line terminal which normally biases to assume a position rela- 25 tively distant from the xed line terminal, a

fuse holder, a lower fixed terminal-engaging element on the fuse holder rotary with respect to the ilxed line terminal, said fuse holder having an open lower end, an axially movable terminal- 30 engaging element at the upper end of the fuse holder, a fuse link connecting said terminalengaging elements and holding them relatively closely together, the upper cantilever line terminal and the movable terminal-engaging element 35 being related so that when the fuse holder is rotated into closed-circuit position the cantilever is deflected to bias the movable terminal-engaging element upwardly and to'tension the fuse link, the movement of the movable terminal- 40 engaging element being such as to clear the cantilever in its normal operating position when the fuse link separates, and spring means reacting between the fuse holder and its movable terminal-engaging element to maintain the latter in 45 maximum spaced relationship from the iixed terminal-engaging element after the fuse has broken.

5. A fuse comprising a xed line terminal, a springing cantilever line terminal having a cam end and an adjacent notch and normally biased to a position away from the fixed line terminal, a fuse holder, a xed terminal-engaging element on one end of the fuse holder rotary with respect to the fixed line terminal, an axially movable terminal-engaging element at the other end of the fuse holder, a fuse link joining the terminalengaging elements to hold the movable engaging element relatively near the xed engaging element, means on the movable engaging element engageable with said cam end upon rotation of the fuse holder and cooperative with the notch in nal position to deect said cantilever toward the fixed line terminal whereby the fuse link is tensioned, the movement of the movable terminal-engaging element being enough that when the fuse link separates and the cantilever line terminal biases the movable terminal-engaging element said terminal-engaging element will clear the notch.

6. A fuse comprising a ilxed line terminal, a springing cantilever line terminal having a cam end and an adjacent notch and normally biased to a position away from the fixed line terminal,

a. fuse holder, a. xed terminal-engaging element on one end of the fuse holder rotary on the fixed line terminal, an axially movable terminalengaging element at the other end of the fuse holder, a fuse link joining the terminal-engaging elements to hold the movable engaging element relatively near the fixed engaging element, means on the movable engaging element engageable with said cam end upon rotation of the fuse holder and cooperative with the notch inl final position to deflect said cantilever toward the xed line terminal whereby the fuse link is tensioned, the movement of the movable terminal-engaging element being enough that when the fuse link separates and the cantilever line terminal biases the movable terminal-engaging element said terminal-engaging element may clear the notch, and a spring reacting between the fuse holder and the movable termlnal-engaging element to maintain said clearance.

THEODORE BIRKENMAIER. 

